It does help if you have an oscilloscope, because then you can see of the "power" is "dirty" or pure DC.
Bob does have a point about the converter....it will be a constant current converter as LED's require a current (which is proportional to their brightness) and they develop a fixed voltage drop.
A large capacitor in parallel with the input to that "converter" and a couple of Shottky diodes, like those dual ones you find in switchmode supplies (with about 30v peak inverse rating) should work.
If not, then you need to draw the circuit diagram of EVERYTHING, all the camper wiring, all the stuff inside all converters and power supplies, all battery chargers involved etc., then apply a holistic approach to the whole lot.
I can't count the number of times I have encountered these "black box" solutions that never quite work as they are expected to because people make assumptions as to what is inside the "black boxes". i.e. Power Supply Unit, LED control unit, Battery Charger Unit, Inverter Unit etc.
This seems to be a very prevalent issue with people who have campers or boats and one recurring issue is the discontinuity of the 0v reference or "Eatrh" line. If you are using solar panels and MMPT's, (Maximum Power Trackers) with the panels, many designs of these do active things with MOSFETS and Diodes on the COLD SIDE, so the negative of the panels is not "Earth"....this catches many out and is also poor design by the "black box" manufacturers. "Earth" discontinuity can also sometimes be an issue with chargers and power supplies too, so it is always a good idea to draw the circuit diagrams of everything before you proceed, then you can see how to fit it all together and if anything is producing an output, requiring an input, has a different reference other than "Earth" or lacks input-output isolation that is NOT what you had assumed initially bey reading the product's brochures!
I feel that many manufacturers of such products "deliberately" make the brochures vague, use poor design practice or are just plain ignorant of design issues such as input-output isolation that cause end-users endless headaches, catastrophic failures and loss of time and money.
If I were to have a camper or boat, based on my past experiences with the campers and boats of others I have been called to attend to...I would purchase good quality complex black boxes like MMPT's, with very good manuals...and for all the less complex stuff, i.e. constant current LED drivers, DC-DC converters, chargers and the like...I would build all of them myself using design apps supplied by chip manufacturers like ST. I would ensure that "Earth" is always the reference line and that isolation, where required would be very high and reliable.
